AXENIC CULTURE OF PARAMECILMSOME OBSERVATIONS ON 

 THE GROWTH BEHAVIOR AND NUTRITIONAL REQUIRE- 

 MENTS OF A PARTICLE-BEARING STRAIN OF 

 PARAMECIUM AURELIA 299X 



Anthony T. Soldo* 

 Department of Cancer Chemotherapy, Schering Corporation, Bloomfield, New Jersey 



The genus Paramecium comprises a group of free Uving ciUates noted for 

 their morphological and genetical complexity. For these reasons and because 

 the organisms represent an end point in a divergent course of evolution, this 

 genus has been an object of interest. Certain members of this group exist in 

 association with self reproducing, intracytoplasmic particles.'- Recent ad- 

 vances in the knowledge of the nutritional requirements of Paramecium has 

 made it possible to cultivate these particle-bearing paramecia in sterile medium. 

 The purpose of this paper is to summarize the present state of knowledge of 

 the nutrition of Paramecium and to present the results of some detailed studies 

 on a particle bearing strain, Paramecium aurelia 299X. 



Nutrition of Paramecium. In the past, Paramecium was cultivated in a 

 medium consisting of plant extracts, notably cerophyl and lettuce infusion, 

 supplemented with living bacteria, usually Aerobacter aerogenes? The first 

 successful report of axenic cultivation was made by Johnson and Baker in 

 1942.4 These workers grew Paramecium multimicronucleata in a medium con- 

 sisting of pressed yeast juice and proteose peptone. Two components of the 

 pressed yeast juice were recjuired for growth. One proved to be heat labile 

 which they assumed to be a protein, but was later replaced by a mixture of 

 ribosidic derivatives of a purine and a pyrimidine; the other was a heat stable 

 component. In 1949, van Wagtendonk and Hackett successfully established 

 P. aurelia in a medium composed of equal parts of 0.5 per cent yeast autolysate 

 and a 24-hour culture of A. aerogenes in lettuce extract.^ This medium could 

 be heat sterilized and provided the basis for later work which led to the de- 

 velopment of a more complex bacteria free medium.^ Folic acid, riboflavin, 

 thiamine, and a steroid proved to be absolute requirements for the growth of 

 stock 5L7 of P. aurelia; the steroid requirement could be satisfied by ^- and 

 7-sitosterol, fucosterol, brassicassterol, stigmasterol, and A'*'"-stigmastadie- 

 none.'^'* Miller and van Wagtendonk found that P. aurelia required 11 amino 

 acids, nicotinic acid, panothenic acid, and possibly, pyridoxal.'^ Also, one or 

 more essential growth factors remained in the yeast. Miller and Johnson 

 studied further the nutrition of P. multimicronucleata, and demonstrated, in 

 addition to the purine and pyrimidine requirement for that organism, a need 

 for an exogenous source of a fatty acid. '"■'•' Recently Lilly et al. cultivated 

 Paramecium caudatuni in a medium chemically defined, except for a single 

 component.''* Their medium was similar to the one used for the cultivation of 

 P. aurelia and P. multimicronucleata, except that it was necessary to add mi- 

 crogram quantities of a protein concentrate obtained from dried green peas. 



* Present address: Department of Contractile Proteins, Institute for Muscle Diseases, Inc., 

 New York, New York. 



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